History is usually a good guide for understanding elections. Even times of unease and upheaval don't repeal the basic laws of politics. But history can also be a trap, blinding us to inflection points that shift the river of public life into a new course.

Case in point: The past predicts that any presidential candidate who lacks experience and credentials might spark a brief moment of interest, but will eventually fade as voters get serious. Three Republicans ran as amateurs this time around, and two them -- Carly Fiorina and Ben Carson -- closely followed that pattern of flaring novelty and rapid decline.

But Donald Trump defied history and won the nomination. So the question is: why? What did so many pundits, politicians and experts fail to see when Trump announced his candidacy a year ago? There are many answers, but two are at the top of the list.

The overall economic picture is pretty solid: declining unemployment, modest inflation and a healthy stock market. But those numbers mask a level of economic frustration that Trump (like Bernie Sanders) has clearly and cleverly tapped.

As Gerald Seib wrote in The Wall Street Journal: "The recession that started in 2007 and the financial crisis of 2008 and 2009 scared and scarred the electorate more deeply and more permanently than has been recognized before."

Wages for many workers have declined or stayed stagnant. A Federal Reserve study found that only 23 percent of American families expect their incomes to rise next year. Underemployment is chronic. One in five families have no members in the workforce at all. Two out of three Americans say the country is headed down the "wrong track."

That pessimism is particularly pronounced among a core Trump constituency: older male blue-collar workers without college degrees. They are slammed by the loss of manufacturing jobs, and unable to take advantage of new opportunities that require advanced skills and schooling.

Exit polls in Republican primaries tell the story: The less education voters have, and the more worried they are about the economy, the more likely they are to support Trump.

Most political analysts, including us, are not likely to know many voters who feel that way. We move in circles and live in neighborhoods where our friends and their children have access to higher education and good jobs. That could help explain our failure to anticipate Trump's appeal.

A second development we didn't fully grasp: Trump's mastery of the media that he uses to spread his message. Few members of the pundit class (again, we include ourselves) ever watched "The Apprentice," a highly successful TV show for 14 seasons. Trump has been a star for a long time, with the name recognition and performance skills that go with that status.

He keenly understands that television thrives on two qualities: outsized personalities and dramatic conflict. The character he played on "The Apprentice" fully exploited those qualities, and so does the character he's playing now on "The Candidate."

Trump might be an amateur politician, but he is a professional entertainer. A lot of us missed that.

Trump shrewdly sensed another key shift: the economic vulnerability of TV networks that have lost audiences and revenues. He delivers those audiences, and TV executives are ecstatic. "(Trump's popularity) may not be good for America, but it's damn good for CBS," admitted Les Moonves, the network's president.

According to one study, Trump received almost $2 billion worth of free TV coverage through March -- far more than the other 16 Republicans candidates combined. (Hillary Clinton received about $750 million worth.)

Trump understands new media very well, too. The Pew Research Center recently reported that 62 percent of Americans now get some news online, and Trump is a constant presence in the digital space, blasting out comments at all hours to his more than 8.5 million Twitter followers.

This gives him three enormous advantages: 1. His tweets are injected directly into the media conversation, unfiltered by independent critics. 2. They are often edgy and outrageous, compelling attention from old media outlets. 3. His followers feel part of the Trump Broadcasting Network, ready to transmit his missives almost instantly to their own connections.

"I don't think anybody has seen anything like this," Fox News anchor Bret Baier told The New York Times.

No, we haven't. Trump's success is a stark reminder that historical patterns don't always repeat themselves.

All of us who study politics have learned a hard lesson. By not taking Trump seriously, we aided and abetted the rise of a totally unqualified candidate.